Process for the automatic removal of copper from ordnance



ALAIN ELIE ALFRED DAGORY, 01? B015 COLOMBES, FRANCE.

I ROCESS FOR THE AUTOMATIC REMOVAL OF COPPER FROM ORDNANCE.

Be it known that I, ALAIN ELIE ALrRnn DAGORY, a citizen of the FrenchRepublic,

.and residing in Bois Colombes, Seine, 8

Avenue Robert Bain, France, have invented certain new and usefulImprovements in and Relating to Processes for the Automatic Removal ofCopper from Ordnance, of which the following is a completespecification.

This invention relates to a process for automatically freeing guns ofall calibers from the copper which is deposited during the firing in theinterior of the bore.

After a certain number of shots have been fired especially when they arefired rapidly, and when guns are employed having grooves the pitch ofwhich is not progressive, there is produced in the grooves and on theribs between them, deposits of copper which are derived from the drivingbands of the shells. This. metal adheres very strongly to the walls ofthe bore of the gun and the effect thereof is to interfere with thefunction of the grooves and consequently act prejudicially on theaccuracy of the firing. It also accelerates in an appreciable manner thewear of the guns by increasing the strain on the grooves and it may goso far as to cause the bursting of the gun.

The operation which consists in removing this copper, and is ordinarilycalled decoppering, takes place rapidly and automatically by utilizingthe process which constitutes the subject matter of the presentspecification.

This process is based on the afiinity which tin when in a state offusion has for copper and on the property which these two metals possessof forming together compounds of relatively lowmelting point and in allcases lower than the temperature attained by the powder gases during thepassage of the projectile through the bore of the gun.

The method consists in covering the base of the shells with a metalliccomposition composed of tin and lead.

By way of example one may be cited which gives good results and consistsof the following proportions viz. 55 per cent. of Sn (tin) and 45 percent. of Pb (lead).

These metals, previously melted together, are arranged on the base ofthe projectile, either over the whole of its surface or in the form of aring around its circumference. The quantity necessary varies with thecali- Speciflcation of Letters Patent.

Patented Nov. 16, 1920.

Application filed July 9, 1920. Serial No. 395,030.

bers proportionally to the surface of the bore of the gun, taking as abasis the figure of 10 grams for a 75 mm. gun.

As soon as the powder gases have made their action felt and theprojectile has commenced its course through the bore of the gun, thelayer in question becomes fused.

he tin and the lead the melting points of which are 232 and 325respectively present in fact the property of forming compounds of adisaggregation point which varies according to the proportions of one orthe other metal, and the minimum melting point of which corresponding tothe eutectic mixture of tin and lead is 187.

If it be considered that the temperature attained in the bore of the gunby the powder gases is of the order of from 2000 to 2200 it will bereadily understood that in the presence of such an excess of temperaturethe disaggregation of the composition of tin and lead adhering to thebase of the projectile takes place almost instantaneously. Examinationof blank trial shells which were fired and found intact in the groundafter firing leave no doubt as to the production of this phenomenon.

The tin and the lead, being reduced to the liquid state are projected,by the centrifugal force due to the rotation of the shell along thewells of the bore of the gun, in the form of fine small drops which arebrought into contact with the copper. This latter metal then forms withthe tin fusible alloys as has been explained above, the copper and thetin giving rise in fact to the formation of a. eutectic mixture composedof 97 per cent. of tin and 3 per cent. of copper the melting point ofwhich is 220.

With the proportions of per cent. of Sn and 40 per cent. of Cu thedisaggregation point is still only 625. Seeing that in the present case,there is an excess of tin, the conditions of temperature necessary tothe disaggregation of the compounds which are formed are thus certainlyrealized.

As regards the lead, it does not combine with the copper but under thecircumstances it plays the part of a lubricant. Its adhesive power isnot comparable to that of the copper, and it disappears on the passageof succeeding shells along with the fusible compounds of tin and copper.

Experience has shown that even a few shells covered on their bases withtin and lead are suflicient to remove the copper from a gun. In the caseof the 75 mm. gun for example, the number of shells necessary does notexceed lf). Of course shells thus prepared and fired from a gun in goodcondition, prevent all obstruction of the grooves and the ribs betweenthem, by the copper.

It goes without saying that the proportions of tin and lead above givenas examples may be subsequently modified according to the exigencies ofpractice, as also may the nature of the fusible metals employed.

The metallic composition of tin and lead or other metals, intended toproduce the removal of the copper from the gun may not only be placed onthe base of the projectile, but also in any other manner, on conditionof course that this composition is subjected, the moment the shot isfired to the heat developed by the combustion of the powder. Thus forexample it is possible:

1. Instead of placing the alloy on the base section to place it on thecylindrical part behind the driving band. This method has certainadvantages in the case of shells which are of truncated conical form atthe rear.

2. To introduce the metallic composition into the shell or cartridgecase.

The alloy may be placed either in the powder charge or immediately infront of it. It may be employed in any form e. g. VVashers, pastilles,powder, granules, etc. In this case it is the extremely rapid movementsof the powder gases which bring about the contact between the alloy inits liquid or volatilized state and the copper deposited on the bore ofthe gun.

Finally, experience has proved that the figure of 10 grams of alloygiven as a basis for use with the 75 mm. shell, is in no way absolute.It may be considerably reduced.

What I claim is:

l. A process for the automatic removal of copper from ordnanceconsisting in bringing into contact with the copper deposited either inthe grooves, or on the ribs between the same or in the smooth part ofthe bore of the gun, a body which forms with the said copper an easilymelting compound at the temperatures which exist in the said bore duringthe firing of the gun, in order to cause the fusion of the copper, andthen its driving out of the gun.

2. A process for the automatic removal of copper from ordnance,consisting in bringing into contact with the copper deposited either inthe grooves or on the ribs between the same, or in the smooth part ofthe bore of the gun, tin in order to constitute with the said copper aneasily melting compound at the tel'nperature existing in the gun durmgthe passage of the projectile through the bore of the gun.

3. A process for the automatic removal of copper from ordnance,consisting in bringing into contact with the copper deposited either inthe grooves or on the ribs between the same, or in the smooth part ofthe bore of the gun a compound of tin with lead, in the followingproportions: tin, to lead, 40% to 41.5%; thus effecting, on the one handthe combination of the said tin with the said copper deposited in thebore of the gun, and, on the other hand, the lubricating of the shellsby the said lead.

4. In a proces for the automatic removal of copper from ordnance, thestep which consists in bringing into the gun together with the load, acompound of tin with lead.

5. In a process for the automatic removal of copper from ordnance, thestep which consists in putting onto the rear part of the shell, acompound of tin with lead which is soldered on the said rear part of theprojectile, the said compound being then, at the firing of the gun,projected by the centrifugal force due to the rotation of the shellalong the walls of the bore of the gun, in the form of fine small dropswhich are brought into contact with the copper.

6. In a process for the automatic removal of copper from ordnance, rearcircular face of the of tin with lead, the said compound to be projectedalong the walls of the bore of the gun, and brought into contact withthe copper.

7. In a process for the automatic removal of copper, from ordnance,applying to the shell a compound of tin with lead, the said compound tobe projected along the walls of the bore of the gun and brought intocontact with the copper deposited on the said walls.

In testimony whereof I have hereunto set my hand at Paris, France, this23" day of June, 1920.

ALAIN ELIE ALFRED DAGORY.

fastening onto the shell a compound

